Bath Nation

I don't think any other country has quite as much fun in the bathtub as the Japanese do. The Japanese suggest 12 home bath brews, one for each month of the year.

This month, November, is the "mikan-yu", or tangerine bath.

This is about the time of year that the Japanese start eating this small citrus fruit and spend the evening sitting under their kotatsu (low, heated tables) watching television. So maybe it's no surprise that the sweet aroma of the mikan fruit would find its way to the bath waters. According to a Japanese website, Yu-no-Kuni (meaning something akin to 'Bath Nation'), one should take the peels of about 20 mikan and dry them. Then wrap the dried skins in a cotton gauze bag (or thin towel) and drop it in the bath.
And just to show you how seriously the Japanese take bathing (move over rubber ducky), take a look at this graph:

The graph is from a study done by the Tokyo Gas Company to measure how well the skin holds heat in the bath. In regular bath water, represented by the lower, blue line, the skin heats up by only a fraction and then loses that heat rather quickly. In comparison, with a tangerine bath, the surface of the skin gains nearly 3 degrees Celsius (about 5 degrees Fahrenheit) and maintains heat for about 50 minutes. Amazing research and I hope the scientists all took a long, hot bath after they published their results.
But there's no need to make a science project out of it. Enjoy some tangerines (mikan are also known as satsuma oranges) and save the skins for the bath. Mikan skins even have a special name in Japanese - chinpi - and they can be used to make a cleaning solution too. Boil 400cc of water and 4 chinpi and then have at it. I suppose you could even use it to clean the bath tub.